Modulated portable signaling or test transmitter



A ril 14,1970 f 3,506,919

MODULATED PORTABLE SIGNALING OR TEST TRANSMITTER D. N. FISTELL Filed July 21, 1967 INVENTOR. 0/?!0 flffisnsz L W Thug ,mgiw .1 5 w United States Patent 3,506,919 MODULATED PORTABLE SIGNALING OR TEST TRANSMITTER David N. Fistell, 1001 Bannock St., Denver, Colo. 80204 Filed July 21, 1967, Ser. No. 655,134 Int. Cl. H03b 5/24 U.S. Cl. 325-105 4 Claims ABSTRACT OF THE DISCLOSURE A miniature transistor oscillator circuit energized by 1.5 v., hearing-aid battery cell, all encased in a portable, suspendable, tubular, insulated container closed at its upper extremity with a threaded cap having a metallic contact band which, when the cap is tightened, contacts a second contact band on the container, to close the battery circuit to the oscillator so as to emit a modulated radio frequency signal from an antenna pin at the lower extremity of said container.

The invention is particularly useful for: locating circuits and circuit elements in electrical and electronic devices; for tracing individual conductors in multi-conductor phone cables; for locating paths and passages for electrical conductors, antenna leads and other electrical conductors in building structures; for locating metallic conduits, pipes and other metallic elements in the walls and floors of such structures; and for injecting a signal into R.F. audio circuits for testing for a signal or lack of signal therein. Other uses will become apparent to those skilled in the art from the following specification.

The principal object of this invention is to provide a miniature, self-contained, self-energized and encapsulated transistor oscillator which can be readily carried in the hand and lowered from the roof or attic through the walls and floors of a building to locate a passage for an antenna lead and which, when in its final position, can be located by simply passing an electronic receiver, such as a pocket-type transistor radio, over the exterior faces of the building structure to enable the receptacle hole to be cut at the proper position.

Other objects and advantages reside in the detail construction of the invention, which is designed for simplicity, economy, and etficiency. These will become more apparent from the following description.

In the following detailed description of the invention, reference is made to the accompanying drawing which forms a part hereof. Like numerals refer to like parts in all views of the drawing and throughout the description.

In the drawing:

FIG. 1 is an enlarged, side elevational view of the portable location signal transmitter of the invention;

FIG. 2 is a similarly enlarged, vertical, diametric sectional view of the transmitter showing the relative locations of the internal circuit elements therein;

FIG. 3 is a circuit diagram of the transmitter; and

FIGS. 4, 5, and 6 illustrate typical adaptors which can be applied to the transmitter for different purposes to be hereinafter described.

The transmitter is enclosed in and supported by a vertical, tubular, molded, cup-like barrel' 10 of'plastic or other suitable electrical insulating material. The open upper extremity of the barrel 10 is internally threaded, as

3,506,919 Patented Apr. 14, 1970 p CC the closed bottom 14. In actual practice the barrel is /2" in diameter and 2" in length.

The cap. 13 is formed with a concentric, upwardlyextending spring socket 16 containing an axially-positioned, compression spring 17 which normally projects below the nipple 12 of the cap 13. A suspension pin 18, terminating in an open loop 19 at its upper extremity, is molded, or otherwise mounted, in the cap and projects upwardly therefrom and is electrically connected to the spring 17 within the cap.

A cylindrical metallic upper contact band 20 surrounds the base of the cap and circumferentially projects downward below the bottom thereof. The upper contact band is electrically connected to the spring 17 by means of an internal conductor 21. A second lower metallic contact band 22 is fixed about the upper open extremity of the barrel 10 and projects above the barrel in circumferential alignment with the upper contact band 20 so that when the cap is screwed tightly onto the barrel, the two bands will contact each other so as to close an electrical circuit.

The circuits and elements, of a conventional inductive-- coupled transistor oscillator 31, as enclosed in the broken line rectangle in FIG. 3, are mounted in the hollow interior of the barrel as shown in FIG. 2. The oscillator 31 employs an encased inductive coil 23 the primary of which is modulated by a condenser 24 and a grid or base lead resistor 25 to supply current to the base of a transistor 26. The emitter of the transistor 26 is coupled by a conductor 36 to the lower contact band 22 on the barrel 10. The collector of the transistor 26 is connected to the secondary of the coil 23, to oscillate at a modulated, permanentlytuned radio frequency and is connected, through a coupled resistor 27 and a diode 28, to supply a rectified D.C. half-wave, modulated signal of corresponding frequency to the antenna pin 15, through a coupling condenser 29 which acts to isolate the suspension pin 19 from the antenna pin 15 to reduce the possibilities of damage from accidental shorts across live external AC. and D.C. circuits. The resistor 27 and the diode 28 have been added to the conventional oscillator circuit to produce a more distinctly audible signal due to the separated half-wave effect.

The above oscillator is energized by a one and one-half v. battery 30, of the type usually employed in hearing aids. The battery 30 is positioned in the top of the barrel 10 on the center tap of the case of the coil 23 so that the spring 17 will contact the positive pole of the battery and urge the negative pole thereof against the center tap of the coil 23 to complete the positive battery circuit to the upper contact band 20 of the cap 13.

Should it be desired to increase the radiation from the antenna pin 15 an extension pin, such as shown at 33, FIG. 4, may be telescopically fitted over the antenna pin 15 to increase the length and the radiation field thereof. The extension pin also serves to more conveniently reach difficulty accessible elements in various electronic circuits. If it is desired to detachably couple the antenna pin 15 to a conductor for testing or tracing purposes, an alligator clip, such as shown at 34 in FIG. 5, may be telescopically fitted over the antenna pin 15.

If the transmitter is to be used in crowded, complicated circuits where a multi-directional emission would interfere with probing and tracing. A metallic, shielding sleeve 32, such as shown in FIG. *6, having an internal diameter to enable it to be snugly slid over the barrel 10, can be positioned as indicated in broken line at 32 in FIG. 1 to reduce lateral wave transmission and concentrate the emission at the antenna pin 15. However, where a wide field of radiation is desired, it is advisable to remove the shielding sleeve 32 from the barrel .10. To renew or replace the battery 30, it is only necesary to remove the cap 13 and dump the used battery from the barrel 10 and replace it with a new battery. Replacement of the cap causes the spring 17 to automatically contact the battery and threading the cap tightly into position on the barrel automatically closes the battery circuit through bands 21 and 22.

The pin 18 and its loop 19 is more particularly for suspending the transmitter by means of a cord in building structures. However, it all serves as a positive lead, when the bands 21 and 22 are out of contact, for testing continuity and for locating a single conductor in a multi-conductor cable, the lower band 22- being used as the negative lead to complete the test circuit to the oscillator.

While a specific form of the invention has been described and illustrated herein, it is to be understood that the same may be varied within the scope of the appended claims, without departing from the spirit of the invention.

Having thus described the invention what is claimed and desired to be secured by Letters Patent is:

1. A portable location-signaling transmitter comprising:

(a) an elongated, tubular, insulated, cup-like barrel having an open upper extremity;

(b) an insulated cap threaded into and closing the upper extremity of said barrel;

() a metallic antenna pin axially projecting from the lower extremity of said barrel;

(d) a battery enclosed in said barrel; and

(e) a transistor oscillator circuit enclosed in said barrel energized by said battery; and

(f) a coupled resistor and diode modulator in series between said oscillator circuit and said antenna pin to radiate a modulated R.F. signal from said pin.

2) A portable location-signaling transmitter as described in claim 1 having attachment means mounted on said insulated cap whereby said barrel may be suspended from a suspension element one pole of said battery being electrically connected to said attachment means.

3. A portable location-signaling transmitter as described in claim 1 having:

(a) a first annular, metallic band connected with a pole of said battery and surrounding the lower extremity of said insulated cap; and

(b) a second similar annular, metallic band in series with said oscillator circuit mounted on and surrounding the upper extremity of said insulated barrel and positioned so that when said cap is threaded into said barrel said two bands will annularly and mechanically contact each other to close a circuit between said battery and said oscillator circuit.

4. A portable location-signaling transmitter as described in claim 2 in which said modulator acts as rectifying means in series between said oscillator circuit and said antenna pin to rectify the signal emitted by the latter to a modulated, half-wave frequency.

References Cited UNITED STATES PATENTS 2,593,432 4/1952 Freas 325-112 2,946,963 7/ 1960 Lee 331-53 X 3,227,948 1/ 1966 Cheshire 200 X FOREIGN PATENTS 918,061 11/1960 Great Britain. 1,040,628 10/1958 1 Germany.

OTHER REFERENCES Lafayette Radio Electronics, 1966 catalog 660, pp. 233 and 243.

ROBERT L. GRIFFIN, Primary Examiner B. V. SAFOUREK, Assistant Examiner U.S. Cl. X.R. 

